BER Analysis of Equalized OFDM Systems in Nakagami, m < 1 Fading

The orthogonal frequency division multiplexing (OFDM) transmission scheme is currently experiencing increased popularity due to advances in very large scale integration technology. It is used for a variety of broadband systems such as asymmetric digital subscriber lines, very-high-speed digital subscriber lines, digital video, and audio broadcasting, and wide local area network standards such as IEEE 802.11a, IEEE 802.11 g, and ETSI Hiperlan/2. However, propagation impairments can cause severe degradation in bit error rates (BER) for coherent detection. We derive a semi-analytical method to evaluate BER of a quadrature phase shift keying (QPSK)-OFDM system in Nakagami, m < 1 fading and additive noise where pilot-assisted linear channel estimation and channel equalization are used. This allows modeling of more severe fading environments than can be depicted by a Rayleigh distribution. Numerical simulations are used to validate the proposed methods. The techniques developed can be applied to other channel estimation techniques, modulation schemes and the performance evaluation of equalized single carrier narrowband systems.